There would also be the issue of the NP200 front output/front drive shaft interfering with the case of the NP205. You would have to use a Ford NP205 (driver's side drop), or clock the Chevy NP205 and NP200 so the front drive shaft clears, or cut the front output part of the case off of the NP205 and weld on a new cover like this:
http://www.pirate4x4.com/forum/showp...5&postcount=20

If you feel you really need a doubler, I think it would be easier to get a NP203 and do the proven 203/205 doubler.